Experimental Study On Influencing Factors Of Diffusion Radius Of Overburden Isolation Grouting Filling Material

Overburden isolation grouting filling is an important technical method for coal gangue emission reduction.The diffusion law of coal gangue slurry is an important theoretical basis for the selection of slurry particle size.In order to determine the optimal particle size of coal gangue abrasive slurry,the thesis comprehensively uses theoretical analysis,experimental research and other means to study the slurry diffusion radius under the condition of coal gangue overburden isolation grouting filling,and determines the influencing factors of slurry diffusion radius.The diffusion radius of overburden isolated grouting filling slurry was studied by theoretical analysis.Guided by the form of solid phase particle migration,the slurry diffusion radius is divided into suspended load migration distance and bed load migration distance.The relationship between slurry particle size and slurry diffusion radius is established by theoretical analysis.By simplifying the mining overburden fracture,it is regarded as a smooth plate fracture.Through the analysis of the force of solid particles in the two-phase flow slurry of coal gangue,according to its motion equation and migration form,the calculation formula of grouting slurry diffusion radius considering slurry particle size is derived.The particle density,slurry density,viscosity and sedimentation rate of slurry with different particle sizes were measured.The results show that the slurry particle density and slurry density do not change with the change of slurry particle size.There is no regular change between slurry viscosity and slurry particle size.The slurry precipitation rate increases with the increase of slurry particle size and is proportional to the slurry particle size.A visual variable opening constant pressure grouting simulation test system was designed to study the diffusion law of various particle sizes under different grouting pressures,grouting materials and fracture openings.The results show that the diffusion radius of the slurry is inversely proportional to the particle size of the slurry,that is,the diffusion radius decreases with the increase of the particle size of the slurry;when the fracture opening is constant,the diffusion radius of the same particle size slurry increases with the increase of grouting pressure.When the particle size is the same,the diffusion radius of coal gangue slurry is larger than that of river sand slurry,which reflects the influence of slurry bulk density on slurry diffusion.Under the same particle size condition,the slurry diffusion radius is proportional to the opening of the injected fracture,that is,the slurry diffusion radius increases with the increase of the opening of the injected fracture.The study found the limit diffusion phenomenon of slurry with different particle sizes,that is,the slurry diffusion radius no longer changes with the grouting time.The results show that the diffusion radius of this kind of slurry conforms to the three-stage law of ’faster in the early stage,slow increase in the middle stage and constant value in the later stage ’.The limit diffusion radius of slurry with different particle sizes was obtained by experiment,and the theoretical calculation formula of slurry diffusion radius was modified,which provided a theoretical basis for the selection of particle size of filling slurry for coal gangue overburden isolation grouting.This thesis contains 45 pictures,5 tables and 140 references.